Humans and gorillas 'closer than previously thought'

Humans and gorillas have a lot more in common than appearances suggest, a Cambridgeshire study has shown.

Across 15 per cent of their genetic code, or genome, gorillas are closer to humans than chimpanzees. In both, certain genes have also evolved at the same rate, research shows. They include genes for hearing, throwing into doubt theories linking the development of hearing and human language.

The findings emerge from the first completed genome sequence, or genetic “blueprint”, of the gorilla. Gorillas are the last of the living great apes to have their genetic codes mapped, allowing scientists to compare the genomes of humans, chimpanzees, gorillas and orang-utans.

The new research was chiefly based on DNA taken from Kamilah, a female western lowland gorilla. Scientists at the Wellcome Trust Sanger Institute in Hinxton, Cambridgeshire, searched more than 11,000 genes in the gorilla, human and chimpanzee looking for important evolutionary differences.

In all three species, genes related to sensory perception, hearing and brain development showed accelerated evolution. But this was especially true for humans and gorillas.

Dr Chris Tyler-Smith, senior author of the research published in the journal Nature, said: “Our most significant findings reveal not only differences between the species reflecting millions of years of evolutionary divergence, but also similarities in parallel changes over time since their common ancestor.

“We found that gorillas share many parallel genetic changes with humans including the evolution of our hearing. Scientists had suggested that the rapid evolution of human hearing genes was linked to the evolution of language.

“Our results cast doubt on this, as hearing genes have evolved in gorillas at a similar rate to those in humans.”

Gorillas separated from humans and chimpanzees on the evolutionary path around 10 million years ago, the research showed. A more gradual divergence between eastern and western gorillas occurred much more recently in the last million years or so. This could be compared with the split between modern humans and Neanderthals, or chimpanzees and bonobos, said the scientists.

Co-author Dr Aylwyn Scally, also from the Sanger Institute, said: “Using DNA from Kamilah, a female western lowland gorilla, we assembled a gorilla genome sequence and compared it with the genomes of the other great apes. We also sampled DNA sequences from other gorillas in order to explore genetic differences between gorilla species.”